1. Field of the Invention
The present invention is in the field of hydraulic accumulators and more particularly pertains to a unit having an improved seal arrangement between the pressure vessel and the oil input fixture.
2. The Prior Art
As conducive to an understanding of the present invention, reference is made, by way of example, to U.S. Pat. No. 3,733,262 wherein there is disclosed a hydraulic accumulator which includes an oil port within which is mounted an oil conduit fixture. In the construction of the subject patent, means is provided for locking the fixture in the oil port in such manner that the fixture cannot be inadvertently removed while pressure remains in the interior of the vessel.
Such construction is advantageous in that, in the absence of such a system, the plug or oil conduit fixture may be violently expelled from the pressure vessel by the retained pressure, with consequent injury to a worker.
In accordance with the device of the subject patent, the outlet plug, consisting of a component of the oil fixture, incorporates a cylindrical shank portion having a radially extended flange at its upper end, the outer diameter of the flange being less than the inside diameter of the bore of the oil port to permit its insertion therethrough. The plug is maintained in position by a locking assembly comprising a pair of arcuate metallic segments united by an annular elastomeric member.
The assembly of the device is effected by folding the locking member at the break line defined between the segments and inserting the same into the interior of the pressure vessel and passing the plug into the vessel and through the locking assembly so that the flange portion of the plug rests on the segments. An O-ring is then introduced into the annular space defined between the plug on the inside and the oil port on the outside. Thereafter, a collar member having a sleeve is positioned over the plug such that the O-ring is interposed between the sleeve of the collar and the lower end portion of the annular segments. A locking nut mounted on the shank of the plug is threaded upwardly to compress the O-ring between the sleeve and the locking segments, whereby an effective seal is formed at an annular area by the compressed and, hence, radially distended O-ring.
As will be readily recognized from the above description or from an inspection of the above referenced patent, the construction of the patent requires the disposition of an O-ring which, for purposes of forming an effective seal, must preferably be slightly oversize, into a small annular space between the oil port and the oil conduit plug.
In view of the extreme pressure involved, even minor scratches or abrasions of the O-ring effected upon insertion of the same may result in substantial oil leakage across the abraded portion of the ring and outwardly through the oil port. The sensitivity of the ring to damage, coupled with the desirably oversize nature of the O-ring, render the positioning of the ring a tedious and timeconsuming process which must be effected with a great deal of care if leakage is to be avoided.